Train speed profile braking system



United States Patent 3,524,055 TRAIN SPEED PROFILE BRAKING SYSTEM Willis R. Smith, and Vincent P. Kovalcik, Rochester,

N.Y., assignors to General Signal Corporation, Rochester, N.Y., a corporation of New York Filed Dec. 19, 1967, Ser. No. 691,741 Int. Cl. B611 3/06 US. Cl. 246-484 Claims ABSTRACT OF THE DISCLOSURE A system for generating speed profiles for stopping different length trains at a station platform which is set into operation when each train passes a control point in approach of the station platform wherein Vernier and car length counters and a bias counter are preset to manifest in combination a particular distance to go to stopping point, and the vernier and car length counters are driven down incrementally as the train progresses in accordance with input to the Vernier counter from an axle driven frequency generator after initiation upon the train reaching an approach marker at the wayside. The bias counter takes into account the relative lengths of the trains and controls the point of initiation of the generation of the stopping profile so that different length trains are stopped at a position substantially centered relative to the station platform.

BACKGROUND This invention relates to automatic operation of trains, and it more particularly pertains to methods and apparatus for generating stopping profile signals to stop different length trains at positions substantially centered opposite a station platform.

If different length trains are to be stopped by following a desired stopping profile at a position centered opposite a station platform, generated in a system such as is disclosed, for example in the Hughson Pat. No. 3,218,454, the starting of the generation of the stopping profiles must be at different approach points in accordance with the different train lengths. To provide separate approach profile initiating, markers and associated apparatus at the wayside for each different length train and associated identity responsive apparatus on each train would be complicated and expensive.

SUMMARY OF INVENTION According to a preferred embodiment of the present invention, only a single approach control marker is required for initiating a stopping profile, this marker being the starting point for generating a stopping profile for the shortest train. However, distance to go counters are started at this point for all trains, irrespective of their lengths, and when a number of car lengths is counted into a bias counter comparable to the additional number of cars in the train over a predetermined number, a stopping profile for that train is initiated. A vernier counter is provided for counting small increments of distance such as the cycles of an axle-drive frequency generator. When a distance has been counted comparable to a larger increment, such as the length of a car, there is an input generated for a car counter, or index counter, and the vernier counter is reset to start counting in small increments the distance traveled comparable to another car length. Storage means is provided for storing a designation of one-half the number of cars in addition to the number of cars in the shortest train, and this storage is compared with the car count in a bias counter that receives car length counts until it manifests the same number of cars as the storage, At this time, the automatic control of the train according to a computed stopping profile is initiated. The computing of the stopping profile is continuously governed by distance to go to stopping point information obtained from the counters, It is to be understood that the counters can all be of the same conventional digital counter type, and that the different names for the counters have been used to more particularly characterize the counters as to their functions.

An object of the present invention is to provide distance to go to stopping point information for each of a plurality of trains of different lengths so that all trains can be stopped automatically in position substantially centered alongside of a station platform.

Another object of the present invention is to selectively initiate the computing of stopping profiles for different length trains at respective different distances beyond an approach marker as measured in accordance with the operation of distance to go counters, one of which counters being set in accordance with the length of the train.

Another object of the present invention is to substantially continuously generate a distance to go to stopping point signal for use in generating a stopping profile as a result of combining outputs of a plurality of counters which initially register, in combination, the total distance to go to stopping point and which have increments of distance travelled subtracted from the distance to go manifested by the counters as a train progresses.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed as the description of the invention progresses.

In describing the invention in detail, reference is made to the accompanying drawings wherein similar reference characters are used to designate corresponding parts in different figures and wherein:

FIG. 1 illustrates by block diagram one embodiment of the present invention as applied to the stopping of trains at a station platform; and

FIG. 2 illustrates more in detail the train carried apparatus of a typical train illustrated in FIG. 1.

With reference to FIG. 1, wayside apparatus is illustrated comprising a station platform 20 beside a stretch of railway track having track rails 21 and 22. The wayside apparatus is arranged for traffic from left to right, and an approach marker SZM is provided for registering on each train when the train has reached a point that is a predetermined distance D in approach of a desired stopping point 2 at the station platform 20 for the front end of a two car train.

Throughout the travel of a train through the distance D, the train is governed by a continuously variable signal corresponding to desired velocity profile. This velocity profile, or programmed velocity, is a function of train position in that its value at any location is proportional to the square root of the distance to go to the stopping point. For trains of different lengths, the same distance is used for the stopping of each train according to the computation of a velocity profile, but the longer trains are permitted to proceed further into the station platform by delaying the start of their velocity profiles until after the trains have progressed a predetermined distance beyond the station start marker SZM. In this manner, each train is stopped substantially centered at the station platform, the front ends of two, four, six, eight and ten car trains being stopped at positions 2, 4, 6, 8 and 10 along the station platform respectively.

A platform marker PEM is located near the entering end of the station platform as a means for correcting the distance to go signal that is used in the computation of the reference velocity profile on a train. This corrects for any inaccuracies in computation that may be caused by wheel wear, for example. A center marker CLM is provided at the center point C of the station platform as a means for providing further distance to go correction as will be more readily apparent as the description of the invention progresses. The marker CLM is actually a wheel detector that generates a pulse for each axle of each car. These pulses are applied through a wheel presence detector 23 to a divide-by-four counter 24 which generates an output pulse for each car which is supplied over wire 25 to control carrier keying apparatus 26. An occupancy detector 27 is provided for detecting occupancy in the section of track adjoining the station platform 20, and such detection is used for initiation of an F8 transmitter 28 and a tone 4 generator 29 upon the entrance of a train into the track section at the left-hand end of the station platform. Ouput of tone generator 29 modulates the F8 frequency and output of the transmitter 28 is applied to the track rails 21 and 22.

This embodiment of the present invention is particularly adapted for use in electrified propulsion areas in that the transmitters are coupled through the track rails to the train by means of impedance bonds. Thus the marker ISZM, for example, has an F8 frequency transmitter 30 which is modulated by output of a tone 1 generator 31. The marker SZM thus provides for continuous energization of the track rails at its location with an audio frequency F8, which is modulated by tone 1. The marker PEM has an F8 transmitter 32 which is normally transmitting through the track rails and which is modulated by an output from a tone 3 generator 33. These markers may be a part of track circuits for conventional train protection systems,

or they can be separate markers provided only for the purpose of use in controlling the stopping of trains in accordance with the requirements of practice. The energy applied to the track rails at the various marker locations provides for the automatic stopping of trains approaching the station platform 20, such as the train 34 which is illustrated as having receiver coils 35 and 36 for sensing energy in the respective track rails 21 and 22. This energy is used to govern automatic train operation apparatus 37 on the train.

With reference to FIG. 2, the train carried automatic train operation apparatus 37 of FIG. 1 is illustrated more in detail. This apparatus comprises a carrier receiver 40 which receives and amplifies alternating current signals received from the track rails 21 and '22 of FIG. 1 by the receiving coils 35 and 36 which are carried by the train. An SZM marker detector and stick 41 is activated in response to the cessation of tone 1, which becomes effective when the front end of the train passes marker SZM. A CLM detector and stick 42 is provided for detecting when the front wheel of the train has actuated the wheel detector CLM. A carrier loss detector 43 is activated in response to the keying by carrier keying apparatus 26 (see FIG. 1) of the F8 transmitter 28. A PEM detector 44 is activated in response to the passage of the front end of the train over the marker PEM in accordance with the cessation of reception by the receiver 40 of the tone 3.

A distance to go signal is determined basically by the sum of count manifestation of three counters. One of the counters is a vernier counter 45 that is a conventional counter which counts down in small increments of distance travelled in response to signals generated by an axle drive frequency generator 46. A second counter 47 is a conventional counter that counts down in increments of car lengths, this counter being controlled jointly by the vernier counter 45 and by a bias counter of car lengths 48. The bias counter 48 is a conventional counter that counts up from zero, while the other counters count down from a setting to zero. Reference can be made to FIGS. 2A and 2B of Auer et al. Pat. No. 3,305,828 for a more complete disclosure of the setting and count down to zero of a digital counter such as may be used in the system according to the present invention.

A comparator 49 is provided for determining when the count in the bias counter corresponds to a number characteristic of the relative length of the train that is stored in a train length storage 50. Digital to analog converters 51 are provided for converting the counts manifested by the counters to analog values. These analog values are combined algebraically by an operational amplifier 52 which generates a single output analog signal characteristic of distance to go to the stopping point for the train. This signal is used as an input to a stopping profile generator 53 which generates a reference velocity signal V which is compared in a deviation detector 54 with an actual velocity signal V to generate an error signal for controlling vehicle propulsion and braking apparatus 55.

Having thus considered the general organization of the system for one embodiment of the present invention, more detail consideration will now be given with reference to the mode of operation.

OPERATION As has been pointed out with reference to FIG. 1, if each train is to be centered opposite the station platform, a two-car train will stop with its front end at the point 2, a four-car train will stop with its front end at point 4, etc. The train length storage 50 (see FIG. 2) is present in accordance with the length of the train, it being assumed that the shortest train is a two-car train which requires no setting in the train length storage 50. The train length storage 50 is set to M2 the number of cars in the train above the minimum two-car train. Thus, if the train is a six-car train, for example, the train length storage 50 is set for two car lengths because the train must stop two car lengths beyond the stopping point for the front end of a twocar train. To illustrate the mode of operation of the system, it will be assumed that a six-car train approaches the station platform 20. Thus the train length storage 50 is set to manifest a count of two.

When the train approaches the marker SZM, the frequency F8, modulated with tone 1, is received on the train. When the front wheel of the train passes the marker SZM, the F8 frequency molulated by tone 1 is shunted by the front axle of the train, and thus the SZM detector and stick 41 on the train is rendered active. This detector remains active throughout the stopping of the train at the station platform. The SZM detector and stick 41 now deliver an output over wire 56 to set the vernier counter 45 to one car length (a distance of 70 feet), and to set the counter 47 to a count of one less than the total number of car lengths from marker SZM to stopping point for the shortest train. The sum of the distance registered at this time in the counters 45 and 47, for purpose of illustration, is assumed to equal 34 car lengths total, which is the distance D of FIG. 1 over which the stopping profile is generated.

The rendering active of the SZM detector 41 also conditions and AND gate 57 to apply inputs on wire 58 to the vernier counter 45 of increments generated by the axle frequency generator 46. These increments can be generated, for example, at a rate of one pulse for every .5 foot traveled by the train. The generator 46 can be considered as including a single-shot multivibrator for forming these pulses. The 70 foot distance that has been set in the vernier counter is reduced by the increments applied over wire 58 until it reaches 0, at which point a zero detector 59 provides an input through AND gate 60 and OR gate 61 to the car length counter 47. This input to the counter 47 reduces the count in that counter by one car length and also generates a one count input to the bias counter 48 through AND gate 62. The AND gate 62 is rendered active by a NOT gate 63 which is controlled from comparator 49. The NOT gate 63 delivers an output to the AND gate 62 until the comparator 49 detects that the number of car lengths manifested by the bias counter 48 corresponds to the number of car lengths in the storage 50. Each time that the zero detector 59 delivers an output to the counter 47 in accordance with the vernier counter 45 having been operated to its zero condition, an output through the AND gate 60 is applied over line 64 to rerest the venier counter 45 to a one car length setting. When the Vernier counter 45 becomes operated for the second time to zero, the output of the zero detector 59 operates as described to reduce the count by one car length in the counter 47 and to add a count to the bias counter 48. The zero detector also provides a second output over line 64 to rerest the Vernier counter 45 to a count comparable to one car length.

At this time, there is a count of two car lengths in the bias counter 48, which corresponds to the two car lengths stored in storage 50 (it being assumed that the train under consideration is a six-car train). The comparator and stick 49 now generates an output to turn off the AND gate 62 and prevent further car counts from entering the bias counter 48. This is done by application of energy over wire 65 to the NOT circuit 63. An output is also applied from the comparator and stick 49 over wire 66 to an AND gate 67 to permit a generated error signal to be used by the vehicle propulsion and braking apparatus 55 to control the stopping of the train. The comparator 49 has a stick feature to maintain the gate 67 energized throughout the balance of the stopping operation.

From the above described mode of operation it will be apparent that the use of a generated velocity profile to control the train has been delayed for two car lengths after passage of the train past marker SZM because of the train being a six-car train, it being desirable to stop the train with its front end two car lengths beyond the stopping point for the shortest train. At the time gate 67 is enabled, the sum of the counts in all three counters 45, 47 and 48 is equal to the distance D over which the stopping profile is to be generated. Outputs of these counters are converted to analog signals in the converters 51, and the analog signals are combined in operational amplifier 52 to provide a distance to go signal input into the profile generator 53. This distance to go signal will be decreased a small amount for each increment applied over wire 58 as an input to the Vernier counter 45. The profile generator 53 has an output speed signal V which corresponds to the desired speed of operation for the train. The speed signal V is compared with an actual speed signal V which is obtained from the axle generator 46 through a suitable amplifier 68. These signals are compared in deviation detector 54, which provides an output error signal through AND gate 67 to the vehicle propulsion and braking apparatus 55. This signal can be of one polarity or another, characteristic of whether the actual velocity is higher or lower than the reference velocity. Thus the train is automatically controlled by the vehicle propulsion and braking apparatus 55 to operate according to the reference speed V generated by the profile generator, and the train is brought to stop at the desired position at the station platform.

An additional feature of the system is that the distance to go signal is corrected from time to time during the progress of the train throughout the stopping pattern in order to correct for wheel wear and other inaccuracies that may occur. The first correction is made when the front axle of the train passes over the marker PEM at the entering end of the station platform. When this occurs, the PEM detector 44 on the train is momentarily rendered active, and it provides an output over wire 69 that resets the counters 45 and 47 to the distance to go from the location of the marker PEM to the stopping point for the front end of a two-car train.

After the train reaches the center point C (see FIG. 1) in the station platform 20, the distance to go registered in the counters 45 and 47 is corrected each time the front axle of a car reaches the detector coil CLM. To accomplish this mode of operation, the carrier F8 and tone 4 are applied at the leaving end of the station platform in accordance with the detection of the presence of the train at the station by occupancy detector 27.

As the train approaches the center of the station platform, the receiver 40 picks up the carrier frequency F8, modulated by tone 4. When the leading axle of the train passes the wheel detector coil CLM, the wheel presence detector 23 momentarily suppresses transmission of the carrier F8 and removes tone 4 for the balance of the stopping operation. Because of the loss of the modulated carrier, the CLM detector and stick 42 on the train is activated and maintained active to provide an output signal for the balance of the stopping operation. Output from the CLM detector 42 is applied over wire as an input to a NOT gate 71 which in turn disables the AND gate 60 for the balance of the stopping operation. This is done because the detection of the first axle of each car at the centerpoint in the station platform is now used to reset the vernier counter 45 and at the same time to reduce by one count the car lengths manifested by counter 47. The detection of the front of the train at the center of the station platform sets the counter 45 to one car length and sets the counter 47 to zero. The energization of wire 70 is then effective to transfer the number of car lengths stored in the bias counter 48 into the counter 47 and in turn sets the bias counter 48 to zero.

The detection of the arrival of the first axle of each car at the center point of the station platform is manifested on the train by the momentary activation of the carrier-loss detector 43, which generates an output pulse on wire 72 each time a first car axle is detected by the wheel presence detector 23 in combination with the divide by four circuit 24 (see FIG. 1). Each output pulse of the carrier loss detector 43 is applied over Wire 72 to set the Vernier counter 45 to one car length and to subtract one count in the counter 47. The count is subtracted in counter 47 in accordance with an input from line 72 through an AND gate 73 and through OR gate 61. Energy is being applied to AND gate 73 at this time by an output of the CLM detector 42. When the counter 47 has counted down to zero, this counter applies inhibit energy over wire 74 to the carrier-loss detector 43 to prevent this detector from generating another output for setting vernier counter 45.

When the total of the distances of all three counters reaches zero, the train has reached its stopping point and has been stopped because of the reference speed signal V having been reduced to zero. Having thus completed the description in detail of a typical mode of operation for stopping a particular length train, it should be readily apparent that a similar mode of operation is effective for stopping a train of a different length, except that the length of the train indicated in the train-length storage is different.

Although the particular embodiment described in detail assumes the use of trains having an even number of cars, it is to be understood that a modified embodiment can be used to center trains at a station platform having any different numbers of cars above a minimum number, irrespective of whether the total number of cars is odd or even. In such an embodiment the train length storage 50 can be modified to store the number of half car lengths over the shortest train length. Half car length increments would then be used in general in place of full car length increments as has been described.

In a still further embodiment of the present invention the system can be modified to provide for trafiic in either direction by the location of an approach marker at the right of the station platform comparable to the approach marker SZM. Means would be provided to render the approach markers effective to control only trains which are approaching the station platform.

Having thus described specific embodiments for generating stopping profile signals for the automatic operation of trains, it is desired to be understood that these forms are selected to facilitate the disclosure of the invention rather than to limit the number of forms the invention can assume. While the invention has been described in its preferred embodiments, it is to be understood that words which have been used are words of description rather than of limitation.

What is claimed is:

1. A system for computing stopping patterns for the stopping of diiferent length trains at a station platform comprising;

(a) approach control means partly on each train and partly at the wayside for manifesting on each train the arrival of that train at a station approach point,

(b) vernier counting means initiated by the approach control means for counting small increments of distance traveled,

(c) car counting means for registering a car count each time the vernier counting means has counted a number of small increments substantially equivalent to a car length,

(d) means for resetting the vernier counting means each time a new count is registered by the car counting means,

(e) initiating means for manifesting a time for starting a braking pattern when the number of cars counted into the car counting means corresponds to a number characteristic of the length of the train, and

(f) additional means rendered active by the initiating means and governed by the condition of both counting means for computing a reference speed signal corresponding to a braking pattern.

2. The invention according to claim 1 wherein each train has an axle driven frequency generator and the vernier counting means counts cycles of a signal output of the generator corresponding to small increments of the distance traveled.

3. The invention according to claim 1 wherein means is provided for setting the car length and vernier counting means to counts 'Wherein the sum of the distances registered in the counting means is substantially equal to the distance to go from the approach point to a desired stopping point for the shortest train, and the distance thus manifested in the counting means is reduced as the distance to go to stopping point is reduced after initiation of the vernier counting means.

4. The invention according to claim 1 wherein the initiating means comprises,

(a) storage means for manifesting the number of cars in each train above a predetermined number,

(b) a bias counter for receiving a car length count for each input to the car length counter,

(c) comparator means for comparing the number of car lengths manifested by the storage means and the bias counter, and

(d) gating means controlled by the comparator for manifesting the start of the braking pattern when the same number of cars is registered in both the bias counter and the storage means.

5. The invention according to claim 4 wherein the additional means comprises means for combining and converting outputs of the counters to obtain a single analog manifestation of distance to go to stopping point for the train.

6. The invention according to claim 5 wherein the additional means comprises means governed by the distance to go signal for generating a stopping speed profile.

7. The invention according to claim 4 wherein distance to go correcting means is provided partly at the wayside and partly on each train at at least one intermediate point between the station approach point and a stopping point at the station platform for correcting the distance to go manifested by the counting means.

8. A method for computing stopping patterns for the stopping of different length trains at a station platform comprising the steps of;

(a) manifesting the arrival of each train at a station approach point,

(b) counting with a vernier counter small increments of distance traveled by each train after reaching the approach point,

(e) counting with an index counter larger increments of distance traveled,

(d) resetting the vernier counter by a count corresponding to the number of small increments corresponding to one of the larger increments each time a larger increment is counted into the index counter,

(e) manifesting the number of the larger increments of distance in the length of each train in addition to a predetermined minimum train length,

(f) counting with a bias counter each time a count is entered into the index counter until the bias counter registers said number of larger increments in the train in addition to the minimum train length.

(g) initiating the computing of a stopping braking pattern for a train When the bias counter registers said number of larger increments in the train in addition to the minimum train length, and

(h) computing a braking pattern for each train in accordance with the distance to go to stopping point as registered by a combination of the conditions of the counters.

9. The invention according to claim 8 wherein the method includes a step of correcting the distance to go as registered on the counter when each train reaches at least one predetermined point along the wayside while the braking pattern for the train is being computed.

10. A system for computing stopping patterns for the stopping of different length trains at a portion platform comprising;

(a) approach control means partly on each train and partly at the wayside for manifesting the arrival of each train at a station approach point,

(b) vernier counting means initiated by the approach control means for counting small increments of distance traveled,

(0) index counting means controlled by the vernier counting means for registering a count each time a large increment of distance is measured by a predetermined number of counts of the vernier counting means,

(d) means for resetting the vernier counting means each time a new count is registered by the index counting means,

(e) initiating means for manifesting a time for starting a braking pattern when the number of larger increments counted into the index counting means corresponds to a number characteristic of the length of the train, and

(f) means rendered active by the initiating means and governed by the condition of both counting means for computing a reference speed signal corresponding to a braking pattern for the train.

References Cited UNITED STATES PATENTS 3,268,727 8/1966 Shepard 246-187 3,297,867 1/1967 Archibald 2461 82 3,334,224 "8/ 1967 Allen et a1. 246-187 3,363,096 1/1968 Hughson et a1. 246-182 ARTHUR L. LA POINT, Primary Examiner G. H. LIBMAN, Assistant Examiner US. Cl. X.R. 246-182 

